Means for controlling the working depth of an excavator

ABSTRACT

System for controlling the working depth of an excavator of the type having a shovel or similar earth moving implement fitted at the end of an articulated jib the system including a device comprising a level indicator located at the turret of the excavator and a conduit extending therefrom to a receptacle, including an elastic member mounted on the shovel. The device being filled with a fluid or several non-mixable fluids, and the pressure thereof upon an elastic member varying with changes in the vertical distance between the shovel and the indicator causing a variation of the level within the indicator, which may be utilized for various control purposes, either manually or automatically. The device may be provided with means for compensating for variations in relation to different depths or grades of the excavation.

United States Patent Nilsson Dec. 18, 1973 OTHER PUBLICATIONS Crumrine et al., Geophysics, Vol. XVI No. 3, July 1951, pages 486-493.

Primary Examiner--S. Clement Swisher Att0rneyl-1olman et a1.

[57] ABSTRACT System for controlling the working depth of an excavator of the type having a shovel or similar earth moving implement fitted at the end of an articulated jib the system including a device comprising a level indicator located at the turret of the excavator and a conduit extending therefrom to a receptacle, including an elastic member mounted on the shovel. The device being filled with a fluid or several non-mixable fluids, and the pressure thereof upon an elastic member varying with changes in the vertical distance between the shovel and the indicator causing a variation of the level within the indicator, which may be utilized for various control purposes, either manually or automatically. The device may be provided with means for compensating for variations in relation to different depths or grades of the excavation.

15 Claims, 5 Drawing Figures MEANS FOR CONTROLLING THE WORKING DEPTH OF AN EXCAVATOR A big problem when performing excavating works is to be able to maintain a desired working depth. This difficulty is especially at hand when digging long canals or ditches, where the shovel sometimes must work below the water level. The sight into deep pits is also often made difficult, and with respect to the risk for caving in of the surrounding earth and the swinging jib it is dangerous to have a man standing at the edge of the pit to direct the work.

The present invention refers to excavators of the type having a shovel, a scraper blade or similar earth moving implement fitted at the end of a jib structure mounted at a chassis structure, and the aim of the invention is to make possible for the operator to control the working depth of the shovel from his seat in the turret mounted on the chassis structure or to control and make a gradient having a certain inclination. The invention is characterized in at least one conduit, pliable at least at portions along its extension and filled with a fluid, said conduit being attached to the jib structure in such a manner that it will follow the movements thereof and at one or both of its ends being communicatingly connected to or arranged to act upon a body, which under the influence of the pressure of the fluid will activate a device designed to indicate the pressure exerted on the receptacle.

Some embodiments of the invention are schematically shown on the attached drawings, in which,

FIG. 1 is an elevation of an excavator provided with control means according to the invention,

FIG. 2 more in detail shows the conduit and the components connected thereto according to a further development of the invention,

FIG. 3 on a larger scale shows a device for electronical supervision of the limit positions of the fluid level,

FIG. 4 shows an elevation of an excavator provided with a compensating mechanism to make the control means suitable to perform work on gradients, and

FIG. 5 on a larger scale and more in detail shows the main components included in FIG. 4.

The excavator shown in FIG. 1 is of the well known type and consists of a turret 10, which is mounted on a chassis 11, provided with driving tracks. An articulated jib consisting of two links 12 and 13, respectively, is mounted on the chassis to be swingable about a vertical pivot axis. A shovel 14 is articulatedly mounted at the free end of the jib. The links and the shovel are operated in well known manner by means of pressure fluid actuated rams l5, l6 and 17, respectively, which are governed from an operating post in the turret.

In order to control the depth of the excavating there is provided means comprising a conduit 18, which extends from a point close by the pivot axis 'of the jib at the chassis down to the edge of the shovel. The conduit 18 is on this occasion composed of pieces of tubing 19, which are attached to the links 12 and 13 and a piece of tubing 20 at the shovel. Close by the working edge thereof, and connected to the tubing 20 a receptacle 21 of a type to be described in connection to FIG. 2, is attached. Near by the pivot axis of the jib a level indicator, in FIG. 1 generally denoted by 22, is fitted. This level indicator, as well as the pieces of tubing 19 and 20 are interconnected by shorter pieces of pliable hose 23, 24 and 25, respectively, in such a manner that a continious connection between the receptacle 21 and the level indicator 22 is obtained, and which will follow the movements of the jib.

By mounting the level indicator centrally in the chassis structure it will become comparatively uninfluenced by a possible oblique position of the excavator which is advantageous, as the excavator seldom will stand on level ground, when it performs work.

The receptacle 21 consists, as is best shown in FIG. 2, of a box 26 having ridgid walls, which by means of a partition 27 of pliable material is subdivided into two chambers, of which one is connected to the conduit 11%, and the other, via openings 28 in a rigid intermediate wall, shaped according to the expected maximum deflection of the pliable partition 27', communicates with an air expansion vessel 29. It is evident that the pressure of the pillar of fluid acting upon the receptacle will increase as the shovel is lowered beyond the plane of the level indicator, whereby the partition 27 will be correspondingly deformed and the fluid level within the indicator will sink. This fact is according to the invention utilized to control the working depth of the shovel. As soon as the latter for the first time reaches down to the desired depth, the level of the fluid within the indicator is marked and the operator thereafter only will have to observe this level in order to know when the shovel has reached down to, or possibly passed beyond the desired depth.

The control means may of course be designed in many different ways to suit different conditions. It is thus possible to have a fixed reference value scale, and to make the indicator displaceablle up and down along the latter in such a manner that on each occasion the level may be adjusted to coincide with a reference mark at a desired working depth. When it is not a con dition that the level of. the excavation be completely level the scale may be graded in units of length, whereby it will be possible directly to follow the work performed.

A further embodiment, which on many occations is preferable, is obtained if the level indicator sight tube is stationary and is provided with fixed scale and is connected to a chamber, the volume of which may be varied in such a manner that the fluid level may be adjusted to coincide with a reference mark as soon as the working depth is reached. The actual position of the shovel may during the following excavating work at any time be ascertained by comparing the fluid level with the reference mark.

Such an arrangement is more in detail illustrated in FIG. 3, which principally corresponds to the level indicator 22 shown in FIG. 1. The indicator consists of a sight tube, which is directly connected to part 23 of the conduit. It is however, further connected to a cylinder 30 which defines a chamber 31, in which a piston 32 is movable forwards and backwards in such a manner that a volume of fluid may be displaced within the sight tube. The displacement of the piston 32 is preferably brought about by means of a reversible electric motor 33, which is connected to the piston by means of a threaded shaft 34. This motor is governed by means of a switch (not shown) actuated by the operator. Within sight tube 22 a float 35 is fitted. A source of light 36 and a photocell 37 are mounted on a slide displaceable along the sight tube. A further photocell device 38, 39 is fitted at a fixed level of the sight tube. when the shovel is resting on the ground, piston 32, by means of the electric motor 33, is brought into such a posijion that the pillar of fluid within sight tube will lift (or lower) the float 35 until this reaches a position coinciding with that of the fixed photokell device 38, 39. When the shovel has reached the desired working depth, the first photocell device 36, 37 is moved to a position corresponding to that of the float.

The supply of pressure fluid to the rams and 16 acting upon the jib to vary the position of the same in the vertical direction are governed by means of a swingable lever 40 in well known manner, which is not illustrated here. To both sides of this lever there is a contact member 41 and 42, respectively, which possibly may consist of solenoid valves in the pressure fluid conduits governed by the lever. These contact members 41 and 42 are governed by signals from photocells 38 and 39, respectively, at the sight tube whereby if either of said photocells is activated by the float 35 passing the beam of light the corresponding contact member, 41 or 42 respectively, will lock the level 40, or will nullify the influence of the latter upon the fluid supply, so the links 12, 13 will be stopped at a desired position.

The signals from the lever indicator sight tube may be obtained in many ways. The tube may itself be provided with a bellows actuating a transmitter or contactor, contact members cast in pairs into the wall thereof to be put into communication with each other as the level is raised or lowered within the tube, or inductive transmitters.

On occasions when it is desired to dig a canal or ditch with a constant inclination, it is possible either to change the volume within the hose system continuously by means of the electric motor 33 in a pre-determined manner, or to change the position of some of the pertaining parts in such a manner that the working depth will be successively altered along the canal.

On many occasions it would be unpractical to have the level indicator located centrally in the turret housing. The conduit should therefore be within the housing, preferably arranged in such a manner that a portion thereof, which is made of transparent material, is easily observed from the operators seat.

Some alternative embodiments of components forming part of the invention are brought together in FIG. 2. The part of the conduit intended to be attached to the links of the jib are, as'before, denoted by 18, and the receptacle mounted upon the shovel and enclosing the pliable partition 27 is denoted by 21.

A compensation chamber 45 is mounted generally at the location of the pivot axis of the jib, and should be filled with fluid to about one half of its height. The compensation chamber may be made of transparent material, and be provided with a window to make possible a check of the fluid level therein. A control plug 46 is fitted in the wall of the chamber at the desired level. This compensation chamber is by way of a piece of tubing 47 and a short length of pliable tubing 49, connected to the level indicator 22.

Arranged vertically and made of transparent material, is a runner 50 carrying a scale 51 displaceable in the longitudinal direction. The lower portion of tube 22 and the main parts of the conduit out to and including one chamber in the receptacle 21 is filled with a first fluid, whereas the remaining portion of tube 22, as well as part of tube 47 contains a second fluid. The remainder of tube 47 and the lower part of the reference indicator 45 contains the same fluid as that in the main part of the conduit and the receptacle 21. The two fluids have different colours and are of a nature not to intermix, whereby a distinct plane of division 52 between the two fluids is obtained within tube 22. The first fluid may for instance be coloured water mixed with glycol, while the other is petrol, i.e. a fluid being lighter than water.

The runner 50 may be displaced upwards and downwards along tube 22 in order to bring a selected mark on the scale to coincide with the plane of division, when the shovel has reached the desired excavating depth. Variations in the fluid level with respect to this mark will then serve as a guidance for the operator.

In order to avoid violent variations at the fluid level due to the sudden movements up and down of the shovel during the work, a conduit 53 should preferably be fitted between the upper and the lower ends of tube 22 and throttling means 48 and 55 are fitted within tube 22 at the upper and lower ends thereof, respec tively, both being above the connections of the conduit 53 to the tube 22. An elastic diaphragm S4 is fitted between conduits 53 and 22 at its upper end, to prevent a direct communication between the ends of tube 22 by way of conduit 53, but which is able to take care of sudden shocks in the fluid system caused by big, rapid movements of the shovel. Alternatively there may be connected to the tube 22 a pressure compensating device which acts in the same manner in order to take care of sudden shocks in the fluid system.

Within the vessel 29 of the receptacle21 is a contact member 59 mounted so as to be actuated by the movements of the pliable partition 27. The signals emitted by member 59 may be used to block the movements of lever 40 and thus act a substitute to contact members 41 and 42, or it may be designed to emit a signal to an optic or acoustic signal device 56 or 57 respectively, when the desired depth has been reached.

The embodiments shown in FIGS. 1 3 provide a satisfactory means for performing excavations where the depth is constant, or where it changes in some easily predetermined manner. In order to make possible an automatic adjustment of the volume of the chamber, when making slanting excavations, for instance along a road bank, the arrangement according to FIGS. 4 and 5 may be used.

The excavator is of the same type as the one described in connection to FIG. 1 which consists of a turret M), which is pivotably mounted on a chassis 11 and provided with an articulated jib including two links 12 and 13, of which the latter is connected to a shovel 14. These components are operated by means of rams 15, 16 and 17, respectively.

The portions of the conduit 18 attached to the links are, as well as the level indicator, removed from FIG.

4 for purposes of clarity since two further conduits will be introduced. The receptacle 21, however, is shown at shovel 14.

A chamber with variable volume is connected to the level indicator 31 formed as a cylinder in which a piston 32 is provided with a displaceable piston rod.

When the excavator is brought into the position shown in FIG. 8, and it is desired to cut a gradient with the inclination shown on the drawing, it is comparatively easy to obtain an automatic adjustment of the volume of the chamber corresponding to the changes called for by the work immediately ahead of the excavator. As soon, however, as the jib is swung to an angular position in relation to the longitudinal middle plane of the excavator (which in the drawing is suppossed to be located substantially perpendicularly to the gradient) a more complicated mechanism must be utilized.

The turrent lit) and the jib 12 are swung in relation to the chassis it by means of a driven pinion 66, which cooperates with a gear-rim 61 fixed in relation to the chassis. On this gear rim a gear wheel 62 is pivotably mounted, and is arranged to be locked in different positions by means of a suitable locking device, here shown as a bolt 63. An arm 63 extends radially from the center common to the gear rim and the gear wheel, which center coincides with the pivot axis 64 for the jib and the turret. The lower end of the piston rod extending from piston 32 is attached to this arm, and will thereby be fixed at a point which is excentric in respect of the pivot axis 66.

The gear wheel 62 may be rotated by means of the pinion 66 connected to a motor 67, after the locking means 63 is released whereupon the gear wheel again is locked. The lower end of the piston rod will then be located in the same excentric position with respect of the pivot 64 as before.

The top part of the cylinder 3i is mounted in a guide 68, which is displaceable along a substantially horizontal rod 69 passing through the pivot axis 64. This rod is mountedin a support 76, which is journalled in a pair of brackets 71 within the turret in such a manner that the support and the rod may perform a forwards and backwards movement, while simultaneously being turned together with the turret.

In the position shown in FlG. 5, the top part of the cylinder 31 is located exactly on the pivot axis and no relative movement between piston and cylinder will be brought about, when the turret is rotated. The position of the guide 68 in relation to the rod may be adjusted by means of a manually operated device, here consisting of a lever 72 and a Bowden cable 73, whereby the guide may be displaced to either side of the pivot axis. The guide will then, when the turret is rotated, move along an arc with respect to the pivot axis, whereby a relative movement between piston and cylinder will be brought about. A corresponding volume of liquid will then be pushed into, or withdrawn from the conduit 18, and will have a corresponding influence within the level indicator 22.

The inclination of arm i2 will of course influence the lever within the indicator in a substantial way, but on the present occasion the angular position of arm 13 with repsect to arm 12 will also have a noticable influence.

The position of rod 69, and thus the real position of guide 68, will be determined from link 13 by means of a second Bowden cable '74, which is connected to link 13 by means of a pivotable lever 75. This is connected to the link by means of a pivot '76, and has such a length that the point of attachment for Bowden cable 76 may be brought to coincide with the center of the pivot axis 77 between the two links 112 and 13. The lever is shown in this position in MG. 5 and the cable '76 will then not transfer any movements from link 13 to rod 69.

By means of a further manually operated device, here shown as a pivotable lever 7d and a Bowden cable '79, the lever 75 may be swung in an arc with respect to the axis 77, whereby the movements of link 13 will act upon the position of rod 69, in a manner which may be brought to be a function of the inclination of the gradient.

Instead of the Bowden cables, shown on the draw ings, pressure fluid or electrical mechanisms may of course be utilized for performing the desired functions. The upper part of the cylinder 31 may be fixed in an excentric position, whereas the lower end of the piston rod, by means of devices equivilant to those shown on the drawing, may be displaced suitably for the working conditions with respect to the pivot axis.

instead of a piston 32 working in a cylinder 3i, a differential transformer may be used which emits signals governing motor 33.

With a broad shovel or scraper blade, one receptable 21 may be fitted at each transverse end of the shovel or blade respectively, and by a conduit of its own be connected to different level indicators at the turret to show also the inclination of shovel or blade with re spect to the horizontal plane.

l claim:

ll. Earth-moving apparatus comprising in combination a chassis; a control turret rotatable about a vertical pivot axis; a jib structure mounted at said turret about a horizontal axis and having an earth-moving implement at the end remote therefrom, means for sensing the effective work position of said implement,

and for aprizing an operator thereof,

said means comprising a pressure-responsive sensing fluid receptacle on said implement, a pressure responsive indicator means at said turret, and transmitting means comprising at least one fluidfilled conduit operatively connected to said receptacle and mounted on said jib structure for displacement therewith,

said indicator means comprising a transparent tube operatively connected to said fluid conduit be tween the ends thereof and located in a substantially vertical position at the turret, and means to display a level of thefluid contained in said trans parent tube.

2. The combination as claimed in claim i in which said fluid-receptacle includes opposed variable-volume chambers, one of said chambers communicating with said indicator means, signal-emitting means operatively connected to said outer variablewolume chamber, and auxilliary pressure-imposing means operatively connected to said fluid conduit for providing a supplemental pressure for adjusting the fluid level corresponding to the effective work depth for said implement.

3. The combination as claimed in claim i in which said transparent tube includes float means therein for following changes of the fluid level, signal means responsive to the level of said float means, and control means operatively connected to said signal means for controlling movement of said jib structure in relation to the level of the fluid.

i. The combination as claimed in claim 3 in which said fluid receptacle on said impllement includes a pressure-responsive partition defining variablevolurne chambers, one of said chambers communicating with the fluid conduit and the other chamber communicating with another chamber.

5. The combination as cllaimed in claim 6 in which a sensing device is operatively connected in said other chamber and includes signal means for indicating when a desired implement depth is reached.

6. The combination as claimed in claim 1 in which said transparent tube comprises part of the fluid conduit and contains two distinct fluids which are incompatible for mixing, the liquids forming a plane of division visable at the transparent tube of said fluid conduit.

7. The combination as claimed in claim 6 in which a compensation chamber is operatively connected to and remote from said fluid receptacle, said fluid receptacle includes opposed variable-volume chambers, one of said chambers communicating with said indicator means.

8. The combination as claimed in claim 6 including means operatively connected to said transparent tube for absorbing fluid surges therein due to sudden movements of said implement or said jib structure.

9. The combination as claimed in claim 8 in which said last mentioned means comprises a fluid connection communicating upstream and downstream of said transparent tube, the fluid connection including an intermediate, flexible diaphragm for preventing direct communication between the ends of said transparent tube through fluid connection.

10. The combination as claimed in claim 1 including auxilliary pressure-imposing means operatively connected to said fluid tube for providing a supplemental pressure for adjusting the fluid level corresponding to the effective work depth for said implement, said auxiliary pressure imposing means comprising a fluid motor including cylinder and displaceable piston components, at least one of the fluid motor components being fixed in an eccentric position relative to the pivot axis of the turret, the other component being displaceable along a rectilinear path passing through said pivot axis, said other component being mounted in said turret for rotation relative said pivot axis.

1 1. The combination as claimed in claim 10, in which manually-operated force-transmitting means is disposed in said turret operatively connected to one of said fluid motor components for adjustably positioning the other component along said rectilinear path.

12. The combination as claimed in claim 10 in which said jib structure comprises articulated links, and forcetransmitting means operatively connected to the rectilinear path for moving the same in relation to the position of one of said jib links.

13. The combination as claimed in claim 12, including second manually-operable, force-transmitting means operatively connected to said means operatively connected to said rectilinear path for adjusting the same in relation to the jib position.

14. The combination as claimed in claim 12 including means for turning the fixed eccentric position of the one fluid motor relative to said pivot axis.

15. The combination as claimed in claim 13 including means for turning the fixed eccentric position of the one fluid motor component relative to said pivot axis. 

1. Earth-moving apparatus comprising in combination a chassis; a control turret rotatable about a vertical pivot axis; a jib structure mounted at said turret about a horizontal axis and having an earth-moving implement at the end remote therefrom, means for sensing the effective work position of said implement, and for aprizing an operator thereof, said means comprising a pressure-responsive sensing fluid receptacle on said implement, a pressure-responsive indicator means at said turret, and transmitting means comprising at least one fluid-filled conduit operatively connected to said receptacle and mounted on said jib structure for displacement therewith, said indicator means comprising a transparent tube operatively connected to said fluid conduit between the ends thereof and located in a substantially vertical position at the turret, and means to display a level of the fluid contained in said transparent tube.
 2. The combination as claimed in claim 1 in which said fluid-receptacle includes opposed variable-volume chambers, one of said chambers communicating with said indicator means, signal-emitting means operatively connected to said outer variable-volume chamber, and auxilliary pressure-imposing means operatively connected to said fluid conduit for providing a supplemental pressure for adjusting the fluid level corresponding to the effective work depth for said implement.
 3. The combination as claimed in claim 1 in which said transparent tube includes float means therein for following changes of the fluid level, signal means responsive to the level of said float means, and control means operatively connected to said signal means for controlling movement of said jib structure in relation to the level of the fluid.
 4. The combination as claimed in claim 3 in which said fluid receptacle on said implement includes a pressure-responsive partition defining variable-volume chambers, one of said chambers communicating with the fluid conduit and the other chamber communicating with another chamber.
 5. The combination as claimed in claim 4 in which a sensing device is operatively connected in said other chamber and includes signal means for indicating when a desired implement depth is reached.
 6. The combination as claimed in claim 1 in which said transparent tube comprises part of the fluid conduit and contains two distinct fluids which are incompatible for mixing, the liquids forming a plane of division visable at the transparent tube of said fluid conduit.
 7. The combination as claimed in claim 6 in which a compensation chamber is operatively connected to and remote from said fluid receptacle, said fluid receptacle includes opposed variable-volume chambers, one of said chambers communicating with said indicator means.
 8. The combination as claimed in claim 6 including means operatively connected to said transparent tube for absorbing fluid surges therein due to sudden movements of said implement or said jib structure.
 9. The combination as claimed in claim 8 in which said last mentioned means comprises a fluid connection communicating upstream and downstream of said transparent tube, the fluid connection including an intermediate, flexible diaphragm for preventing direct communication between the ends of said transparent tube through fluid connection.
 10. The combination as claimed in claim 1 including auxilliary pressure-imposing means operatively connected to said fluid tube for providing a supplemental pressure for adjusting the fluid level corresponding to the effective work depth for said implement, said auxiliary pressure imposing means comprising a fluid motor including cylinder and displaceable piston components, at least one of the fluid motor components being fixed in an eccentric position relative to the pivot axis of the turret, the other component being displaceable along a rectilinear path passing through said pivot axis, said other component being mounted in said turret for rotation relative said pivot axis.
 11. The combination as claimed in claim 10, in which manually-operated force-transmitting means is disposed in said turret operatively connected to one of said fluid motor components for adjustably positioning the other component along said rectilinear path.
 12. The combination as claimed in claim 10 in which said jib structure comprises articulated links, and force-transmitting meAns operatively connected to the rectilinear path for moving the same in relation to the position of one of said jib links.
 13. The combination as claimed in claim 12, including second manually-operable, force-transmitting means operatively connected to said means operatively connected to said rectilinear path for adjusting the same in relation to the jib position.
 14. The combination as claimed in claim 12 including means for turning the fixed eccentric position of the one fluid motor relative to said pivot axis.
 15. The combination as claimed in claim 13 including means for turning the fixed eccentric position of the one fluid motor component relative to said pivot axis. 